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Creating a Parfor loop for multiple function evaluation

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H H
H H on 29 May 2017
Answered: Walter Roberson on 29 May 2017
Hello. I want to use parfor to reduce the calculation time for a loop I have by evaluating 6 functions at the same time. Could you please help me out with this:
The general form of the loop in my m file is:
x=rand(100,20);
global fidr_m;
fidr_m= fopen('C:/results.txt','w'); %%???
for i=1:100
Y(i)=func(x(i,:))
end
and my function (func) includes some lines to generate a unique text file from a base file depending on the looping variable (i=1:100) and run a very costly function WW.
function y = func(X)
if isempty(count)
count = 1;
else
count = count +1;
end
BasePath='C:/MyComputer/';
BaseName='Comp';
File = strcat(Basename, BaseName, num2str(count),'.txt');
y=WW(File,X);
XX=[X,y];
global fidr_m;
if fidr_m==-1
error('can not open the file');
end
fprintf(fidr_m, '%f\t', XX);
fprintf(fidr_m,'\n');

Accepted Answer

Walter Roberson
Walter Roberson on 29 May 2017
You do not define count in the function before you use it.
global variables are not copied between workers.
You cannot use a worker to do i/o on a file that you open in a different worker.

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